Remove
Sisko's and Austin's heads with an exacto knife - the boil and pop method
may work, but you'll need to trim the "stems" of the necks in any event.
Remove Sisko's hands at the cuff. Austin's hands will pop off his arms
without any cutting (they're removable) Using a dremel tool, hollow out
the ends of Sisko's arms. While drilling, rotate the tool so that the cuffs
of the sleeves get pushed outwards. (Think bell bottom sleeves here) You'll
need the extra room to fit in the lace frills around Austin's hands. You'll
have to drill pretty far into the arm to fit the hand assembly inside.

Back
on the Austin base figure, remove the "Frilly Lace Cravat" from the front
of the figure, and trim away the collar area. Now you're ready for
final assembly - stick Austin's head onto Sisko's body, insert the hands
(depending on how tight your drilling was, you may or may not have to glue
them in) and glue the lace to the front of the tunic.

If
you want a cool bonus figure from this process, glue Sisko's head and hands
onto the "discarded" Austin body - instant "Disco Sisko"!

PAINTING:

The best part about this
custom for me was that there was NO painting involved! Just be VERY careful
with the dremel tool and exacto knife, otherwise you may have to do some
touchups.